Approximately 26 million Americans are afflicted with either Type 1 or Type 2 diabetes. Despite the use of insulin and oral anti-diabetic medications to help maintain euglycemia, about 60-70% of these individuals develop diabetic peripheral neuropathy (DPN). See Veves, A.; Backonja, M.; Malik, R. A., Pain Med. 9 (2008) 660-674. A number of small molecules based upon the novobiocin scaffold are reported to inhibit heat shock protein 90 (Hsp90), and are reported to have significant neuroprotective properties and to be useful for reversing symptoms of DPN in animal models. See B. R. Kusuma et at., J. Med. Chem. 55 (2012) 5797-5812; U.S. Pat. No. 9,422,320.
One novobiocin analog (“novologue”) of this type is N-(2-(5-(((3R,4S,5R)-3,4-dihydroxy-5-methoxy-6,6-dimethyltetra-hydro-2H-pyran-2-yl)oxy)-3′-fluoro-[1,1′-biphenyl]-2-yl)ethyl)-acetamide (4) which is reported to exhibit high neuronal protective activity. Kusuma (2012). Novologue 4 is further reported to have effects that are dependent upon the presence of another heat shock protein, Hsp70, while other effects are independent of Hsp70. The precise role of Hsp70 in the mechanism of action of novologue 4 and related compounds has not been fully characterized. J. Ma et at., ACS Chem. Neurosci. 6(9) (2015) 1637-1648.
The synthesis of novologue 4 is reported to follow a procedure that results in an amorphous solid, and its physico-chemical characterization omits definitive assignment of stereochemistry at the 2-position (Kusuma (2012); U.S. Pat. No. 9,422,320), thereby allowing in principle for the existence of two possible anomers 4a and 4b as shown below:

The published synthesis of 4 (also known as KU-596), while indicating an HPLC purity of 95.6%, does not indicate anomeric purity of the amorphous solid, as evidenced by the fact that only the noviose 2-position lacks definitive assignment of stereochemistry. (Kusuma (2012).